Early 4020 Injector pump rebuild

MaverickM23 · Jun 7, 2014

Went to start our early 4020 today to bale hay had throttle half way and it started right up but then right away it over revved. Moved throttle all the way back and it slowly idled down but when I give it just a little throttle it goes all the way to 2000 rpms, just kinda runs away. Does this indicate time for a new pump? I've never had the pump off. Had the injectors gone over two years ago. Throttle linkage is fine which leads me to believe its the pump.

Tx Jim · Jun 7, 2014

(quoted from post at 17:46:22 06/07/14) . Moved throttle all the way back and it slowly idled down but when I give it just a little throttle it goes all the way to 2000 rpms, just kinda runs away. Does this indicate time for a new pump?.

Yes inj pump needs repaired before a rod protrudes through the engine block

MaverickM23 · Jun 7, 2014

Ok, I turned the flywheel to TDC in normal rotation
and no mark was visible. So I turned it another full
revolution and the mark was there but its about a
1/16th behind the timing mark is it ok to take the
pump out now? And when it goes back in should those
marks be lined up or a 1/16th behind like they are
now?

Tx Jim · Jun 8, 2014

JDemaris · Jun 8, 2014

I don't know which pump you have. If an early or late DB - sounds like a typical plastic-dampener failure. $50 in parts to fix and labor depends on who does it. Takes 2 hours on the bench.

If a C model pump - there is a rack and pinion gear set that runs the throttle. Very common for it to dry up and the gears wear out. Sometimes a half-hour fix if you can flip the pinion gear over half-way and use the unworn gear teeth.

MaverickM23 · Jun 8, 2014

The numbers on the pump are DBGVC 633 3AJ. Don't know if I should attempt the fix myself or have someone do it, or buy a rebuilt one. The tractor had been loping at low idle lately before this happened.

JDemaris · Jun 8, 2014

The DBGVC stands for "die cast model B, centrifugal governor, vertical mount, clockwise" as I recall.

All the parts come to around $50. For a first timer with a tech manual - it's easy to spend a full day on it. To a person with experience - 1 to 2 hours.

It is no more complicated that rebuilding a Rochester Quadrajet carburetor. Not easy but not that difficult either if careful. No special tools needed other then one special wrench that will cost you $10.

Depends if you want a learning experience . . or just want it fixed and don't want to risk it yourself. A pump shop will not "rebuild" it. They will replace small parts and likely leave the major moving parts as-is. Typical charge is $400 to $700.

Early 4020 Injector pump rebuild

MaverickM23

Member

Tx Jim

Well-known Member

MaverickM23

Member

Tx Jim

Well-known Member

JDemaris

Well-known Member

MaverickM23

Member

JDemaris

Well-known Member

Similar threads